1. Field of the Invention
The invention relates generally to the field of hydraulic valves and, more particularly, to a valve adapter which can be used to convert or retrofit a manually controlled hydraulic valve assembly to an electronically controlled hydraulic valve assembly.
2. Background of the Prior Art
Hydraulic valve assemblies having hydraulic control valves are used throughout the United States for various applications. One common application is for controlling the operation of the conveyor and the spinner on a cinder or salt spreader vehicle. Many different types of such spreader vehicles are known. In these spreader vehicles, the material to be spread, typically cinders or salt, are stored in a large bin or compartment on the vehicle. When material is to be spread on a road, the material is moved by a conventional conveyor, such as an auger, from the bin to the spinner, typically a rotating disc-shaped element. As the spinner rotates, the material is thrown outwardly in an arcuate path and onto the road.
In most conventional spreader vehicles, both the conveyor and the spinner are hydraulically powered. In most older spreader vehicles, a manually operated hydraulic valve system having a manually operated flow control valve is used to control the speed of the conveyor and the spinner. An example of such known manual hydraulic control valves in wide use with spreaders is the 2F series of valves, for example a Model No. 2FFL12-D6-7/15S valve, manufactured by the Fluid Controls Division of the Danfos Corporation of Easley, S.C. Another well known and widely used manual control valve in the field of spreaders is the QDB series of valves manufactured by the Mobile Fluid Products Division of the Dana Corporation of Sarasota, Fla. Both the Danfos 2F series valves and the Dana QDB series valves are manual hydraulic flow control valves and the structure and operation of these valves is well known in the spreader industry. These valves are single or dual pressure compensated flow control valves which must be manually adjusted to change the flow of hydraulic fluid through the valve assembly to adjust the speed of the conveyor or spinner.
A semi-exploded view of a Danfos 2FFL12-D6-7/15 manual control valve 10 in a manually controlled hydraulic valve system 12 is schematically shown in FIG. 1 of the drawings. The manual control valve 10 includes a valve block 14 having a pair of manual valves 16, one of which is shown in exploded view. Each manual valve 16 has a control knob 18 attached to a conventional needle valve 20. The needle valves 20 extend into threaded valve cavities 22 in the valve block 14. The valve block 14 is typically in flow communication with a hydraulic fluid source through a delivery conduit 26 and a return conduit 28. The hydraulic fluid flows through the valve block 14 and through outlet conduits 30 and 32 to the spinner and conveyor, respectively.
The manual control knobs 18 must be turned by an operator in order to adjust the flow of hydraulic fluid through the valve block 14 to increase or decrease the speed of the conveyor and spinner. However, once set, the manual control knobs 18 must then be manually readjusted in order to vary the speed of the conveyor and spinner. This manual adjustment is time consuming and inconvenient. Additionally, such manual control systems maintain the set speed of the conveyor and spinner without regard to the speed of the spreader vehicle. Therefore, if the spreader vehicle is traveling at a high rate of speed, only a thin coat of salt is placed on the road. If the spreader is traveling at a slow rate of speed, a rather thick coat of salt is placed on the road.
A growing trend in the spreader industry is to base the speed of the conveyor and spinner on the ground speed of the spreader vehicle. In these systems, an automatic control system is used which opens and closes a hydraulic valve assembly to increase or decrease the speed of the conveyor and spinner based on the speed of the spreader vehicle traveling along the road. These automatic control systems usually include electric motors that have been adapted to manually open and close a valve stem in an amount proportional to the speed of the spreader vehicle.
More recent developments include the use of electronic or solenoid valve systems to control the spreader hydraulic valves. In these solenoid valve systems, solenoid valves are carried in a valve block specifically designed for these solenoid valves. The solenoid valve system is electronically connected to a control system to open and close the solenoid valves based on the spreader speed. These solenoid valve systems have the advantage over manual systems of adjusting the speed of the conveyor and spinner based on the spreader speed.
For the owners of the older, manually controlled spreader vehicles, it would be advantageous to replace the old manually controlled hydraulic valve system with a newer, electronically controlled hydraulic valve system. However, the cost and time involved in removing the manual valve system from the vehicle and replacing it with an electronically controlled valve system are prohibitive. The old manual valve block and associated manual valves must be removed and replaced in whole with the new valve block having the new electronically controlled valves. This means that the piping in the old system must generally be changed and reconfigured to engage the new valve block, which also adds to the cost of such a change. For most owners of older, manually controlled spreader vehicles, the costs involved in such a valve system change out are not economically practical.
There are electronic valves, such as solenoid valves, commercially available. Two types of solenoid valves in common use include simple open/close valves and pulse width modulated linear proportional throttling valves (PWM valves). The PWM valves are flow control valves which may or may not be pressure compensated. These individual PWM valves are generally available as "cartridge valves" in the industry.
A widely used example of such a cartridge valve is the DF122 series of valves manufactured by Parker Hannifin Corporation of Elyria, Ohio. A conventional Parker Hannifin Model DF122C14-20 cartridge valve (without a solenoid coil) is shown in FIG. 2 of the drawings. The cartridge valve 40 includes a valve body 42 and a movable, spring biased valve rod 44. A valve spool 46 is carried on the lower end of the valve rod 44. The spool 46 is substantially cylindrical in shape having a central, tapered region 50 with a plurality of holes 52 in the tapered region 50. The spool 46 is slidable within a valve sleeve 54 attached to the lower end of the valve body 42. The structure and operation of such a conventional cartridge valve will be readily understood by one of ordinary skill in the art.
It would be useful to be able to adapt a known cartridge valve, such as a DF122 series valve, to be used in the valve block of a conventional manual control valve, such as the 2F and QDB series valves, to convert a manually controlled hydraulic system to an electronically controlled hydraulic system. However, the conventional cartridge valves are typically too large or are of non-compatible configuration or design to fit into the valve cavities of the manual control valve blocks.
Therefore, it is an object of the invention to provide a valve adapter which can be used to adapt a commercially available cartridge valve, such as a series DF122 cartridge valve, to fit into the valve cavities of a manual hydraulic flow control valve, such as the 2F or QDB series manual control valves. It is also an object of the invention to provide a method of quickly and easily converting a manually controlled hydraulic valve system to an electronically controlled hydraulic valve system. It is further an object of the invention to provide a valve assembly for a hydraulic system having a cartridge valve, a valve block and an adapter connecting the cartridge valve to the valve block.